@revertwtf/mcp

Read-only MCP server for agents that encounter EVM, JSON-RPC, wallet, library, simulation, ERC-4337, Blockscout, or x402 errors and need clear next steps without doing a broad internet search.

pnpm add @revertwtf/mcp

pnpm --filter @revertwtf/mcp build
pnpm --filter @revertwtf/mcp start

Local MCP clients can spawn the stdio server through the revertwtf-mcp bin after the package is built.

Connect an MCP client

The server speaks MCP over stdio. Add it to any MCP client (Claude Desktop, Claude Code, Cursor, Cline, etc.). Once published to npm:

{
  "mcpServers": {
    "revertwtf": {
      "command": "npx",
      "args": ["-y", "@revertwtf/mcp"]
    }
  }
}

From a local checkout (after pnpm --filter @revertwtf/mcp build), point at the built bin instead:

{
  "mcpServers": {
    "revertwtf": {
      "command": "node",
      "args": ["/absolute/path/to/revertwtf/packages/mcp/dist/bin.js"]
    }
  }
}

With Claude Code: claude mcp add revertwtf -- npx -y @revertwtf/mcp.

The server is read-only and needs no API keys. It falls back to the catalog JSON shards when the generated SQLite index is absent; set REVERTWTF_CATALOG_DB_PATH to use a prebuilt @revertwtf/search DB in production.

Tools

• explain_error - normalizes and explains raw errors, JSON strings, traces, revert bytes, and x402 facilitator responses.
• decode_revert_data - decodes Error(string), Panic(uint256), and known custom error selectors.
• search_catalog / get_error / catalog_stats / list_sources - browse the reviewed catalog. Search/list tools are backed by @revertwtf/search, bounded, and paginated; use get_error only after selecting a specific id.
• lookup_selector - resolve a 4-byte selector to signature candidates.
• explain_aa_error - explain ERC-4337 AAxx and EntryPoint failures.
• get_blockscout_chain / search_blockscout_chains - inspect the bundled Blockscout chain registry.

Resources

• revertwtf://catalog/stats
• revertwtf://catalog/sources
• revertwtf://catalog/errors/{id}
• revertwtf://catalog/sources/{source}
• revertwtf://blockscout/chains/{chainId}

Payload policy

The MCP server is designed for agents that need one explanation or one search, not bulk data export. Catalog search returns summaries with limit, offset, totalMatches, and hasMore. It does not send the full catalog to clients for a simple lookup.